This invention relates to the treatment of sewage. More particularly, this invention relates to the treatment of sewage discharged from houses and other buildings which are not connected to a municipal sewer system such that, after the sewage has passed through the Aerobic Treatment Plant with Filter Pipe (“ATPFP”), it has been cleaned to a level acceptable for discharge into the environment so that it will not contaminate the ground water. Thus, the ATPFP provides an alternative to septic systems for buildings constructed outside of a local municipal sewer system.
There are several versions of the conventional sewage treatment system which use aerobic microorganisms to break down sewage. One such device is seen in U.S. Pat. No. 5,549,818. This conventional sewage treatment device consists of a cylindrical tank which encompasses a funnel-shaped clarifier. The clarifier divides the cylindrical tank into an outer chamber, between the outer wall of the tank and the clarifier, and an inner chamber, inside the clarifier. Air is introduced into the outer chamber by multiple air droplines, which are connected to an air compressor and which pump air bubbles into the sewage in the outer chamber. Sewage flows into the outer chamber where it comes in contact with the air bubbles. The introduction of air facilitates the breakdown and digestion of the sewage by aerobic microorganisms present in the sewage. The aerated sewage then proceeds into the clarifier through an opening at the bottom of the funnel-shaped clarifier. Inside the clarifier is a quiescent zone. This area of calm in the inner chamber of the device allows for settling to occur, with the solids falling back out of the clarifier and collecting on the bottom of the treatment tank. Accordingly, the waste water becomes cleaner as it progresses upward in the funnel-shaped clarifier, continuing to allow gravity to separate the solids from the water. So, by the time the sewage has progressed up through the clarifier, it has been substantially cleaned. This treated effluent exits near the top of the clarifier and is discharged. This aerobic clarification process has also been combined with a second, post-treatment stage in an earlier invention by the present inventors, as seen in U.S. Pat. No. 6,228,258.
A common problem with such current devices has been that they often do not effectively remove floating debris from the effluent. This may result in a less than satisfactory effluent for discharge to the environment. It may also prevent the use of a pump to discharge the effluent, since the presence of debris would interfere with the operation of the pump mechanism, clogging the pump and requiring an undue amount of maintenance. These problems are amplified in systems which do not include a pre-treatment tank designed to trap trash. Thus, a need has arisen for a compact two-tank sewage treatment plant which effectively overcomes these concerns.
The present invention of the Aerobic Treatment Plant with Filter Pipe (“ATPFP”) improves upon the basic aerobic clarification process for sewage by adding an integrated filter cleaning stage after aerobic clarification of the effluent in order to produce a better effluent, more suitable for discharge to the environment. The filter stage also acts to capture floating debris of the type which would hamper the effectiveness of a pump mechanism. Thus, the ATPFP is able to treat sewage more thoroughly than conventional devices, while also providing the benefits of pump-driven discharge of effluent (as for example, when the effluent is used for landscape hydration in an attached sprinkler system). In effect, the filter pipe of the ATPFP acts as both a filter mechanism and a trash trap mechanism simultaneously, allowing a single compact unit to address both of these important functions.
In the ATPFP, the sewage first proceeds through an aerobic tank, passing through an aeration chamber followed by a settling chamber in a clarifier. Then, in the second stage, the sewage enters a post-treatment area, where it is filtered and may also be chlorinated before discharge. Through this multi-step process, the ATPFP produces a cleaner effluent. The filter traps small floating particles left after the aerobic clarification process, so that the effluent being discharged to the environment is relatively free of debris and particulates. In addition to producing a cleaner effluent, this produces an effluent which can more easily be pumped out of the post-treatment area. The use of chlorine in the post-treatment tank also disinfects the effluent before discharge, ensuring that no disease carrying organisms, which could contaminate the ground water, are discharged from the ATPFP.